Phil Johnson, M.D. discusses why it's so important for HIV/AIDS patients to follow their antiretroviral (ARV) medication regimen as prescribed. During active infection, up to 10 billion HIV particles will be created each day. This provides ample chance for the virus to mutate in ways that provide resistance to the medication. By keeping the blood levels of the ARV medication high, that will keep the viral load low and reduce the opportunity for resistance mutations to flourish. When HIV develops resistance to one medication, it may develop resistance to other ones at the same time. Patients may also have to deal with side effects such as the redistribution of fat in the body and increases to their cholesterol level. Not every patient can tolerate every ARV. Therefore, it's critical for patients to make every ARV last as long as possible. When people with resistant HIV have unprotected sex, they may transmit resistant HIV to their sex partners.